We report on a spontaneous aggregation of specific lipids in a supported membrane with geometrical barriers. When two types of lipids with different effective molecular shapes, correspondingly different spontaneous curvatures, are mixed in a supported membrane, the lipids with a nonzero spontaneous curvature spontaneously aggregate at the geometrical barriers so as to relax the free energy increase resulting from elastic distortions. Further we have found that this spontaneous aggregation is attained without disturbing the physical properties of the supported membrane such as the lateral fluidity. The results show that the geometrical barriers introduced of the solid support provide a viable patterning technique in a supported membrane depending on the particular molecular shapes. (C) 2004 Elsevier B.V. All rights reserved.